Fuel Metering Pump Control FMPC

The FMPC-V2 is an electronic control system (composed of HW and SW parts developed by UNIS company) and together with the brushless DC motor, hydraulic pump and 3-wave solenoid valve presents the FMP (Fuel Metering Pump). The FMP is a part of the APU fuel system. Its main function consists in feeding the gas generator nozzles of APU with the required fuel flow and pressure to guarantee constant turbine speed.

The FMPC-V2 is powered from the 28V primary and secondary on-board systems. The FMPC-V2 is controlled through the START/STOP digital input, RS-422 serial interface or by an analogue input signal for setting up the required fuel flow. The primary function of the FMPC-V2 is to control a six-pole 3-phase brushless DC motor; furthermore, it provides fuel temperature monitoring at the pump inlet, the current consumption, the temperature of power bridge transistors and voltage level supply.

The FMPC-V2 control SW was developed in accordance with RTCA DO178B standards, level B.

FMP architecture

FMPC-V2 main control application has two main states: 

Power-up state

Power-up State serves for initialization of the whole device, performs PBITs (Power-on Built in Tests)

Operational state

In Operational State all the necessary functions for the required behavior are performed, such as communication with ECU, general IO handling (measurement and evaluating of signals, fuel flow regulation and compensation algorithm, rpm measurement, electronic commutation and CBITs (Cyclical Built in Tests). FMP is controlled at variable flow by ECU to maintain the APU speed constant. The FMP unit controls the fuel flow by varying the pump speed for the following APU operations:start the APU (open loop: no closed loop control on APU speed for ECU), maintain the APU speed at a constant value (closed loop control on APU speed for ECU) and transferred to FMP via the digital data bus or/and the analog setting input.

Environmental conditions

The unit meets the RTCA/DO-160F standards.

Technical parameters:

Range of operating temperatures: -55°C to +85°C
Short-time operating temperature: -55°C to +125°C
Range of storage temperatures: -40°C to +70°C
Altitude range: -1000 to 51000 ft
Nominal voltage: +28 V DC
Operating voltage: 18 V up to 32 V DC
Dimensions of FMPC-V2 (L x W x H): 120 x 70 x 73.5 mm
Dimensions of FMPC-S sensor board (L x W x H): 44 x 25 x 9.5 mm
Weight FMPC-V2: 498 g
Weight FMPC-S sensor board: 3 g
Operating period and technical life: 20 000 running hours or 20 years
Motor type: Structure 3-phase with permanent magnets, brushless Number of poles 6